1. Field of the Invention
This invention relates to a rotor for hydrogen-cooled rotary electric machines wherein the rotor is cooled by hydrogen gas.
2. Description of the Prior Art
In rotary electric machines such as hydrogen-cooled rotary electric machine, the following limitations are generally placed on the provision of passages for the gas for cooling the windings at the end of the rotor. A retaining ring for holding the windings in a predetermined position develops stress of high magnitude and it is not desirable to form gas flow passages in the retaining ring. This makes it inevitable to permit the gas to be introduced into and discharged from the windings through an annular surface disposed outside the end surface of the retaining ring and restricted by the rotor shaft. Moreover, the area that can be used for forming the gas inlet and outlet passages is further restricted and becomes essentially smaller than the area of the annular surface because of the fact that laminated windings occupy the major part of the zone between the retaining ring and rotor shaft and a center ring for axially supporting the laminated windings is located beneath the retaining ring. It has hitherto been one of the most important problems in the technology of cooling the windings at the end of the rotor how to provide inlet and outlet ports for the cooling gas under these circumstances.
It has been proposed in the prior art to form grooves in the rotor shaft to increase the area of the gas inlet port for introducing gas into a gas inlet chamber as well as to divide a gas outlet chamber near the polar axis into a first zone near the center ring and a second zone away therefrom with the respective zones communicated to fan-like ventilating means, and to have fan-like ventilating means communicated to a third zone in the gas outlet chamber near the interpolar axis, thereby releasing gases to the outside.
With such prior arrangement, the fan-like ventilating means is provided only at an area near the polar axis, so that it is not possible to enlarge an area for the discharge of gases therethrough and strengthen a driving force for the discharge of gases. In addition, unlike the gases flowing to the first and second zones in the gas outlet chamber, the gases flowing to the third zone are discharged only by one fan-like ventilating means though they include both flows of gases through axially and circumferentially extending channels in the windings. Therefore, sufficient area and driving force for the discharge of the gases can not be obtained to perform an effective cooling of the windings near the interpolar axis.